Fix #19531 [Form] DateType fails parsing when midnight is not a valid time

src/Symfony/Component/Form/Extension/Core/DataTransformer/DateTimeToLocalizedStringTransformer.php

@@ -117,20 +117,29 @@ class DateTimeToLocalizedStringTransformer extends BaseDateTimeTransformer
             return;
         }
 
-        $timestamp = $this->getIntlDateFormatter()->parse($value);
+        // date-only patterns require parsing to be done in UTC, as midnight might not exist in the local timezone due
+        // to DST changes
+        $dateOnly = $this->isPatternDateOnly();
+
+        $timestamp = $this->getIntlDateFormatter($dateOnly)->parse($value);
 
         if (intl_get_error_code() != 0) {
             throw new TransformationFailedException(intl_get_error_message());
         }
 
         try {
-            // read timestamp into DateTime object - the formatter delivers in UTC
-            $dateTime = new \DateTime(sprintf('@%s', $timestamp));
+            if ($dateOnly) {
+                // we only care about year-month-date, which has been delivered as a timestamp pointing to UTC midnight
+                return new \DateTime(gmdate('Y-m-d', $timestamp), new \DateTimeZone($this->inputTimezone));
+            }
+
+            // read timestamp into DateTime object - the formatter delivers a timestamp
+            $dateTime = new \DateTime(sprintf('@%s', $timestamp), new \DateTimeZone($this->outputTimezone));
         } catch (\Exception $e) {
             throw new TransformationFailedException($e->getMessage(), $e->getCode(), $e);
         }
 
-        if ('UTC' !== $this->inputTimezone) {
+        if ($this->outputTimezone !== $this->inputTimezone) {
             $dateTime->setTimezone(new \DateTimeZone($this->inputTimezone));
         }
 
@@ -140,15 +149,17 @@ class DateTimeToLocalizedStringTransformer extends BaseDateTimeTransformer
     /**
      * Returns a preconfigured IntlDateFormatter instance.
      *
+     * @param bool $ignoreTimezone Use UTC regardless of the configured timezone.
+     *
      * @return \IntlDateFormatter
      *
      * @throws TransformationFailedException in case the date formatter can not be constructed.
      */
-    protected function getIntlDateFormatter()
+    protected function getIntlDateFormatter($ignoreTimezone = false)
     {
         $dateFormat = $this->dateFormat;
         $timeFormat = $this->timeFormat;
-        $timezone = $this->outputTimezone;
+        $timezone = $ignoreTimezone ? 'UTC' : $this->outputTimezone;
         $calendar = $this->calendar;
         $pattern = $this->pattern;
 
@@ -163,4 +174,24 @@ class DateTimeToLocalizedStringTransformer extends BaseDateTimeTransformer
 
         return $intlDateFormatter;
     }
+
+    /**
+     * Checks if the pattern contains only a date.
+     *
+     * @param string $pattern The input pattern
+     *
+     * @return bool
+     */
+    protected function isPatternDateOnly()
+    {
+        if (null === $this->pattern) {
+            return false;
+        }
+
+        // strip escaped text
+        $pattern = preg_replace("#'(.*?)'#", '', $this->pattern);
+
+        // check for the absence of time-related placeholders
+        return 0 === preg_match('#[ahHkKmsSAzZOvVxX]#', $pattern);
+    }
 }

src/Symfony/Component/Form/Tests/Extension/Core/DataTransformer/DateTimeToLocalizedStringTransformerTest.php

@@ -230,6 +230,26 @@ class DateTimeToLocalizedStringTransformerTest extends DateTimeTestCase
         $this->assertDateTimeEquals($this->dateTime, $transformer->reverseTransform('02*2010*03 04|05|06'));
     }
 
+    public function testReverseTransformDateOnlyWithDstIssue()
+    {
+        $transformer = new DateTimeToLocalizedStringTransformer('Europe/Rome', 'Europe/Rome', \IntlDateFormatter::FULL, \IntlDateFormatter::FULL, \IntlDateFormatter::GREGORIAN, 'dd/MM/yyyy');
+
+        $this->assertDateTimeEquals(
+            new \DateTime('1978-05-28', new \DateTimeZone('Europe/Rome')),
+            $transformer->reverseTransform('28/05/1978')
+        );
+    }
+
+    public function testReverseTransformDateOnlyWithDstIssueAndEscapedText()
+    {
+        $transformer = new DateTimeToLocalizedStringTransformer('Europe/Rome', 'Europe/Rome', \IntlDateFormatter::FULL, \IntlDateFormatter::FULL, \IntlDateFormatter::GREGORIAN, "'day': dd 'month': MM 'year': yyyy");
+
+        $this->assertDateTimeEquals(
+            new \DateTime('1978-05-28', new \DateTimeZone('Europe/Rome')),
+            $transformer->reverseTransform('day: 28 month: 05 year: 1978')
+        );
+    }
+
     public function testReverseTransformEmpty()
     {
         $transformer = new DateTimeToLocalizedStringTransformer();